Technical Abstract:
Forage production on Western US rangelands can be increased with the right combination of plants. Our objective was to demonstrate the relative forage production advantage of including a legume on dry rangelands. A falcata and rhizomatous alfalfa (medicago sativa L.), alti wildrye [Leymus andustus (Trin.) Pilger], Siberian crested wheatgrass [Agropyron fagile (Roth) Candargy], and two forage kochias [Kochia prostrate (L.) Schrad.] were planted in monocultures and in binary mixtures with the legumes at 100, 75, 50, and 25 cm spacings. Forage yield of the grasses, alfalfas and forage kochias averaged 1.18, 1.42, and 3.28 Mg/ha, respectively. Yield of alfalfa-grass mixtures was 26% higher than grass monocultures. A 4% yield increase was observed in grass-forage kochia mixtures; however, no increase was observed in alfalfa-kochia mixtures. Yield per unit area ranged from no different to 136% higher on the 25 cm spacings compared to the 50, 75, and 100 spacings. However, a greater than 50% reduction in plant height occurred when plants were grown on 25 cm centers. Increased forage production on rangelands will be realized by including legumes and using dense plant spacings; however, the reduced height associated with denser plant populations may restrict grazing during winter months when snow cover is deep.